How is it possible to hack an iPhone 8

Is it jailbroken? If it is, restore it from a backup or set it up as new.

Also, if you are using iCloud Drive, does anyone else have access to your Apple ID account and password? Check all details of your account at https://appleid.apple.com (Security and your Apple ID - Apple Support)

If you think your Apple ID has been compromised - Apple Support

Contact Apple for help with Apple ID account security - Apple Support

Are you running the latest supported iOS version for your device? Again, is it jailbroken?

Without your Apple ID (and passcode if set up) nobody can access your device if it is properly updated and apps coming from the App Store.

They could hack your email account which supports your Apple ID, and with that, access to the contents via https://www.icloud.com . To avoid this happening in the future, see the articles I posted above to secure your account, and change your email account password.

I found all these weird things attached to my phone and weird algorithms

We'll need a something a bit more concrete that 'weird things' and 'weird algorithms'.