I think my iPhone is being hacked

That’s unlikely in the extreme.

What, exactly, are you seeing that makes you say this?

If you haven’t jailbroken your device, it’s almost impossible to hack it.

Almost. The exception is if you are a high value target of a repressive government. The tools required to do this are incredibly expensive. You’re simply not worth the expense.

That does not mean that your online accounts can’t be compromised, especially if you re-use passwords for multiple services and don’t use 2 factor authentication where available.

It's very doubtful you phone is being hacked. What makes you think it is?