Magnetic Field Detector : Free

This app is used to measure magnetic field(EMF), it shows current magnetic field values.
This application detects the nearby emf generated by metal. It uses your phone's built in magnetic sensor.
Just Open the app a check the stats. When any metallic object is near you will see the fluctuating reading go stronger.
To initialize the sensors, point your phone up towards the sky and move it in a figure 8 pattern.