Is there an equation to calculate how much force is needed to turn a gyroscope

You know gyros…the cool levitates at an angle thing…Well since its spinning its supposed to be very stable according to gyroscopic precision. So my question is – Is there an equation to find how much torque is needed to give the gyro so that it turns it axis of rotation? If there is please also explain to me the derivation. Also it would be great if you explain to me how gyros work. An answer to both of those questions would be valued…Help is always appreciated…Thanks in advance