In message , Sue
writes

"Davy" wrote
Moles hunt their prey in pitch darkness; scent is important to them.
So pickled onions in their burrows is probably quite a problem to them
and they will give up and go elsewhere. That maybe another part of
your garden or your neighbours.

Camphor mothballs are sometimes recommended on the same principle, but
some moles will simply push them up and out, or just dig a detour.
There's no easy answer. We reluctantly use a trap when lawn or precious
plants are being undermined, but even when you catch the culprit(s),
sooner or later another mole will occupy the empty runs. It's an
on-going battle of wills!

Jane Ransom hated moles with a vengeance.
--
June Hughes