They shouldn't be microphonic. If you want them to stick, I'd just put a dab of automotive silicone gasket maker (I use the orange kind) on the pickup and press the cover on.
A long time ago, I had a white guitar with white plastic covers. As I remember, I didn't have to do anything but slide them over the pickup, then install them.
The covers stayed on the pickups because the rings held them in place.
A long time ago, I had a white guitar with white plastic covers. As I remember, I didn't have to do anything but slide them over the pickup, then install them.
The covers stayed on the pickups because the rings held them in place.