Hacker is using my iPhone Notes app

Notes sync to email accounts. When you open Notes it shows the email account that a Note came from, so it should be easy to figure out which email account was hacked, and change your password for that account.

No one can “control” your phone, unless you share an Apple ID with them, and even then they can only see content you sync, and can’t control anything.

You should run a safety check on your iPhone→How Safety Check on iPhone works to keep you safe - Apple Support

Yes, probably an email account, maybe a shared Apple account.

Out of curiosity…

Do you have two-factor authentication enabled? If not, go enable that.

Unique and robust passwords in use everywhere? Password re-use is doom.

Reviewed the security recommendations offered in Settings > Passwords?

MrHoffman wrote:

Reviewed the security recommendations offered in Settings > Passwords?

Moved to the Passwords App in iOS 18.