Described herein are methods and devices that use magnetometer in a hearing aid for measuring a magnetic field. The magnetometer may be a high-sensitivity triaxial magnetometer that detects the magnetic field in three orthogonally oriented directions. Such a magnetometer may be placed in the hearing aid without restriction as to location or orientation. The measured magnetic field may be used for telecoil switching when the presence of a magnetic field produced by a speaker or other source is detected. The measured magnetic field may also be used for magnetic mapping of the environment and motion detection.