How can I tell if someone has hacked my iPhone?

Trufamily wrote:

I think that my brother has apple intelligence and thinks it is funny to mess around with my phone he has access to my phone and the internet WiFi how can I prove it

Having Apple Intelligence does not give your brother access to your phone. The only way your brother could have access to your phone is if he has the passcode to either your phone or your Apple Account. Change the passwords on both.

One, if your brother has Apple intelligence then he has iPhone 16, Two, change your passwords now! The one that you use to sign into your phone and all the others that he knows. To prove it you need to catch him at it preferably on camera, but I would talk to him about it, ask him to stop and do step two.

I’m not familiar with Apple Intelligence yet as I am still running a 13. I really don’t see any form of consumer Ai being involved in anything nefarious like that. Your brother might be a different story. Can you provide more details and tell us some of the symptoms?