Disclosed is a cochlear stimulation system and associated methods that utilizes a magnetic field sensor to determine the status of magnetically-coupled components. The cochlear stimulation system includes an implantable portion positionable beneath the skin of a patient and an external portion positionable outside the skin of the patient. The implantable portion includes a multi-electrode array having a plurality of electrodes configured to be placed in cochlear duct of a patient and an internal magnet. The external portion includes a speech processor configured to generate control signals in response to received sound signals and an external magnet. The external magnet and the internal magnet generate an attractive magnetic force that maintains the external portion in position relative to the internal portion against the scalp of the patient. The cochlear stimulation system further includes a magnetic field sensor configured to sense the value of a magnetic field generated by the external magnet and the internal magnet in order to monitor changes in the magnetic field.