There are a few simple features in your iPhone settings that will indicate that someone other than the owner has used the phone.
There are three ways that users can find out if someone else has tried to read text messages on their iPhone, writes The Sun.
Method one
Usually, the user accesses the iPhone's memory when it needs to be cleaned, but checking the memory status can also help identify intruders. You need to go to Settings — General — iPhone Storage, then scroll down to the section where the apps are listed. The filter at the top of the list should be set to Size by default. You need to change it to Last Used Date. This will sort the apps by the time they were last used.
If the user sees that the app was recently opened, but they know for sure that they haven't touched it recently, then someone else has used it.
Method Two
The second tip can be found in the iPhone's Screen Time settings, but it only works if the feature has already been activated in the settings.
The Screen Time feature is designed to help you track and control how much time you use your smartphone. However, it can also reveal key information about when you used your gadget. Settings — Screen Time — View all app and website activity. Then scroll down to the section called Pickups.
In this section, there is a note called First Pickup. This is the first time that the iPhone was used that day, which means you can see whether someone unlocked the smartphone before you did or not. You can track information from previous days to see if this has happened before.
Third way
The third tip can also be found in the Screen Time settings. Settings — Screen Time — See all app & website activity — “Most used today” section.
Then you need to find the app that you could be tracking and tap on it. For example, it could be WhatsApp or Gmail. There you can see the exact time intervals during which the app was used on a particular day and how much time was spent on the app. Therefore, if the user knows that they have not used this application at a certain time, it will become clear that third parties have intervened.