Digital Compass is A basic compass application that shows you which direction your phone is pointed. The heading and cardinal direction are displayed within a rotating display of the compass.
The value under the heading is the magnitude of the magnetic field being measured (in microtesla). Values greater than 65 or less than 25 usually indicate that something is interfering with the device's magnetometer.

Note that metallic objects can distort the device's magnetometer readings and hence the compass. Make sure to keep the device away from metallic objects to get a more accurate reading.