Not sure why you’d want to, but the Cam v3 original mount will attach to the Cam v4. The circular part that attaches to the cam housing is the same, but Cam v4’s square mounting plate on the other end is slightly contoured differently towards the cam side. If you completely collapse the v3 mount down to the v4 housing, it won’t fit flush, but it still works fine. Both Cam v3 and Cam v4 use 1/4-20 UNC screws. The screw heads are the same, but I think the Cam v4’s screw is about 0.5 mm shorter and designed to bottom out. IOW, if you plan on using a Wyze Cam base/mount, you’ll probably want to stick with what comes with the cam.
Cam v3 mount attached to a Cam v4:
Cam v3 with Cam v3 mount (left), Cam v4 with Cam v3 mount (right):
