Records of Activities You Didn’t Do
A common way to hack into an iPhone is with a virus-laden iMessage, email, FaceTime, or similar form of communication that includes sneaky downloads. Hackers will then try to pass these messages along to other people in your contacts. The upshot of this process is that you may find messages on your phone that you didn’t send or remember receiving. These messages will often look blank or have weird symbols that are not things you would type, even accidentally.
Anything like that is an excellent sign that your phone is infected, and is probably sending out infected messages to other people. At this point, it’s time to take immediate action.