A handy app I found today was “Metal Detector” It’s acts as like a “metal detector” sort-of. It uses your IPhone built-in magnetometer, which helps your phone detect the X,Y, Z axes for things like the compass.
I don’t think that Metal Detector will detect everything that’s metal, but why not have fun with it anyway.
Point your phone’s camera toward the metal objects and turn up the dial to increase the intensity. You’ll be surprised by the things it picks up. The app detects any metal that is magnetic.
If you don’t have an iPhone, a similar app (also called Metal Detector) is available for Android devices. These apps share the same name; however, they were created by different developers and have slight differences in the way they operate.
Source: USA Today