Magnetometers are mostly used in archeological surveys, metal detectors, and explorations etc. to detect the mineralization and geological structures. Magnetometers are used to measure the strength of the magnetic field and in some cases direction of the field. A sensor that is attached to this device measures the flux density of the surrounded magnetic field around it.

Since the magnetic flux density is proportional to the magnetic field strength so the output directly gives the intensity or strength of the magnetic lines.

Some of the sources of the permanent magnetism are (like iron, other metals) useful while measuring the magnetic field strength. However, these devices are also making use of the magnetic properties of the nuclei of atoms.