How to Make a Ghost Movement?

How to make a ghost movement?
Imagine a dementor... floating in small movement.
I can't use sinne, since I use pathfinding. Both behavior doesnt work together.
How to do this?

One solution would be to use an animation. You could make the origin move back and forth over the course of the animation.

Another way to do it would be to have an invisible DementorBase, which has the pathfinding behavior and moves in a sane manner, then have a Dementor that either has it's position near the Base, or has some custom movement that sort of lerps toward the base, but keeps it's momentum when it gets too close.