The present invention relates to an apparatus for tracking a device comprising a magnet as the device is inserted through a subject. The apparatus is wearable by the subject and comprises a unit configured to conform to the subject. The apparatus further comprises magnetic sensors arranged with the unit. In use, the magnetic sensors detect magnetic fields of the magnet and the detected magnetic fields are processed to determine a position of the magnet. This allows tracking of the device as the device is inserted through the subject.