detects metals and magnetic filds that works
Metal Detector - measure the value of the magnetic field through a magnetic sensor that is built into your smartphone. (Metal detectors use electromagnetic fields to perform metal detection and others)
Now you can easily find metallic objects that are hidden underground, behind walls etc. You can also see the reading through the graph.
Used by ghost hunters since it detects electromagnetic fields.
App on your cell phone called are used to measure the Earth's magnetic field, but it cannot detect silver, gold, copper coins (non-ferrous - no magnetic field).