you can get ultrasound mole repelers but that would get expensive if you have a large garden. i have been told the little wind mill you buy at the seaside do the same thing, the moles don't like the vibration through the ground.
alternativly i belive a trial was beeing done using low doses of lawn sand this increases the acidity of the soil and drives the earth worms away, with no food the moles will move off to another area. google it see if you can find if that worked. the ferrit option may work but a mole tunnel is a little narrow for a ferrit so it would have to be waiting around for the mole to pop up, i think it woul probably go and find something more interesting to do.. good luck