If you suspect that someone might be using your iOS device to look through your personal information when you're not looking, such as a sibling, spouse, or parent when you're sleeping at night or when you leave your device laying around, then you can use a new jailbreak tweak called CatchY0u
by iOS developer MoonWolf to confirm your suspicions.
Since many of us choose not to use passcodes for the convenience of easily breezing through the Lock Screen, CatchY0u is a nice way to confirm whether or not someone is going into your iOS device when you don't want them to.
The tweak lets you choose your most important applications, and whenever they're opened, your iOS device will snap a picture with the front-facing camera so that the person's face is saved to your Camera Roll. This makes it easy to know who was just using your device, and more importantly, if they were going into any of your important applications.
Your most important applications are set in the CatchY0u application, which is added to the Home Screen rather than a preferences pane in the Settings application:
CatchY0u will make you configure an Android-style drawn password that is used to authenticate yourself before opening the CatchY0u application. Once you get beyond it, you will be brought to a list of installed applications. If you want to enable CatchY0u for an application, just turn it on – turning applications off will disable the tweak for those applications.
While CatchY0u doesn't stop someone from going into your applications and seeing your personal information, it does allow you to see who was trying to go into your personal applications so that you can deal with them later. If you would like to give CatchY0u a try, it's available in Cydia's BigBoss repository right now for $1.99.
iPhone 5 running iOS 7.0.6