can damaging your phone affect its proformance and your data?

An iCloud backup does not include notes. See this for an explanation of what iCloud backs up and doesn't backup. What does iCloud back up? - Apple Support

Here’s what iCloud Backup includes

• App data
• Apple Watch backups
• Call history
• Device settings
• HomeKit configuration
• Home screen and app organization
• iMessage, text (SMS), and MMS messages
• Photos and videos on your iPhone, iPad, and iPod touch¹
• Purchase history from Apple services, like your music, movies, TV shows, apps, and books²
• Ringtones
• Visual Voicemail password (requires the SIM card that was in use during backup)

Your iPhone, iPad, and iPod touch backup only include information and settings stored on your device. It doesn’t include the information already stored in iCloud, like Contacts, Calendars, Bookmarks, Mail, Notes, shared photos, iCloud Photo Library, My Photo Stream, Health data, and files you store in iCloud Drive.

1. If you turn on iCloud Photo Library on your device, your photos and videos are already stored in iCloud, so they aren't included in your iCloud backup.
2. Your iCloud Backup includes information about the content you buy, but not the content itself. When you restore from an iCloud backup, your purchased content is automatically redownloaded from the iTunes Store, App Store, or iBooks Store. Some types of content aren’t downloaded automatically in all countries. Previous purchases might be unavailable if they've been refunded or aren't available in the store. Find out what you can redownload from iTunes in your country and what you can buy from the iTunes Store in your country.

Back up your phone to your computer. Back up your computer.

How to back up your iPhone, iPad, and iPod touch - Apple Support

How to back up your Mac - Official Apple Support

You can also email them to yourself and back them up. You can create PDFs and save the PDFs to a hard drive.

No unless you physically delete them NO, If they are notes synced with iCloud rather than another account (such as Gmail, Yahooo, etc.), you might try adding any missing notes from your phone to your notes on icloud.com, then going to Settings>iCloud, turn Notes off, then turn it back on if for some reason your missing them and can't find them, but as long as you back them up to iCloud they'll always be there!

JasonWeng28000 wrote:

if my notes are connected to my icloud account and a massive apple server failure happends will i still lose my notes?

Oh for the love of a higher power, if you're that paranoid about losing notes, go by a notebook and right down all your notes and then lock it up in a safe..

You're being overkill here man.. relax.

Try to calm down about this. If there is a massive failure of Apple’s servers and their backup systems, then yes, you will most likely lose everything. Is that possible? Yes. Is it likely? Probably not.

You do understand that with redundancy, the chances of a "massive apple server failure" that you are inquiring about are somewhere between slim and none. The chances that everything fails is almost impossible, and they back-up their systems, just like all of us should be doing. I believe you are expecting the zombie Apocalypse and in that case, I believe the status of your notes is not going to matter.

JasonWeng28000 wrote:

has a massive apple server failure ever happended before?

While Apple may have server failures, to my knowledge, they have not resulted in massive lost of customer data. They have a lot of redundancy.

If you're this concerned about your data, you need to think about redundant back up systems. You should be using both a cloud back up and at least two back ups to hard drives. One drive should be kept in secure storage in a different place than your computer. Safety deposit boxes are good. Printing your notes out and storing them in the safety deposit box is also good.

Apple has thousands of servers, and data storage is replicated on multiple servers around the world. This practice, used by all computer server managers, is call “diversity”. By coincidence, this practice is central to a US Supreme Court today, February 27.

if i have my notes connected to my icloud account,i will never lose my notes right?

While the possibility of it happening are very slight, and that has been explained to you ad nauseum here, no one here is capable of guaranteeing that you will never lose your notes.

You are not speaking to Apple here, this is a user to user support forum, so we could not stay with absolute certainly that you will never lose your notes.

Please see: https://discussions.apple.com/thread/8296714

Your question regarding a backup has been answered repeatedly.

JasonWeng28000 wrote:

can damaging your phone affect its performance and your data?

yes.

The short answer is yes.

Most definitely can, depending on how bad and to what extent the damage is, will probably affect it more so