How can I know if my iPhone has been hacked or not?

To hack a phone, a person has to physically have it in order to hack it. In order to protect it, have a good passcode to unlock it, only share that with people you really trust, don’t let anyone use your phone without your presence, have two factor authorization on too.

Unless your husband had your phone for an extended period of time without your knowledge, I doubt it was hacked. At this point, I would suggest doing a backup and then restore it as new through iTunes on your computer. Initially do not restore the backup. Try it for awhile and see what happens. If it works well, then reload the backup and see what happens. If you still have problems, get an appointment at an Apple Store for an evaluation.