IntruderCheck is a free and ad-free tool available for Android devices that helps you detect if someone gets access to your device without your consent. Once enabled, IntruderCheck takes a photo using the front camera of your device once it is unlocked. These images are hidden from photo gallery and file managers, and only you can manage and view them through a passcode-secured application.

To enable monitoring, you need to grant permission for camera usage and turn on "Monitor Unlock Events" or "Monitor Failed Password Attempts" as desired. The timestamp of each record is shown under the picture, and IntruderCheck keeps the most recent 10 unlock events, with no such limitation if you upgrade to PRO mode.

Please note that monitoring failed password attempts requires IntruderCheck to be a device administrator. If face unlock is enabled, it may fail to capture the image. Additionally, if the camera is unavailable, the event will still be recorded with a timestamp.

Overall, IntruderCheck is a useful tool for those who are concerned about the security of their Android devices and want to keep an eye on any unauthorized access.