Voles eat vegetation, moles are good guys. It could be the moles came through to eat your grubs and then the voles moved into their tunnels, or maybe just a case of misidentification. Voles reproduce like crazy. A wildlife speaker said if all their offspring lived and reproduced, in a year one pair of voles could reproduce
enough to equal the mass of an elephant! I had a terrible problem with them years ago, part of what got me to quit growing carrots, potatoes, beets, and even green beans. All was nibbled and destroyed! At the time the only advice I got was to remove all the mulch because they used that to hide from predators. They had tunnels all over the garden just under the mulch. They got so populous they would run across my feet when I went into the garden!
After removing the mulch and a summer with almost no garden they seemed to disappear.
Sorry no answers for you, I hope others can give you some good ideas!