The hacker may install malware or spyware on your phone after it has been compromised. Your battery may slow down and drain more quickly as a result of these background-running apps.
Your phone may heat up if you have background apps running. Because it can lead to battery degradation, overheating poses a risk to your phone. The persistent overheating of your phone may indicate that your device has been compromised by a hacker.
Do you have any apps on your phone that you did not install? This indicates that your device is under the control of a hacker. Go to Settings > General > VPN & Device Management to see which configuration profiles or unknown apps are installed on your phone.
Tell your pals that you may have been hacked and take action as soon as they start complaining that they keep getting odd calls and messages from your number that you didn't send. More on that in a moment.
You should be on the lookout for pop-ups as soon as you start seeing them because Apple devices are known for being effective at stopping them. Watch out for Safari and other programs that may act sluggish or divert you to other pages.