Orlando,

An electronic compass can measure angular displacement within the constraints of the compass and the local magnetic field (pointing error). Electronic gyros measure angular rates. Neither can measure a translational displacement.

Electronic gyros (rate gyros) have a drift error spec. The drift error spec is usually too large to use the gyro to establish an inertial reference by itself. But, if combined with the electronic compass, the drift error can be estimated, thereby minimizing the effect of drift rate at the cost of accepting the electronic compass indication and the associated pointing error.

Have fun,

Bruce