I found the solution - Steps are simple:
In OBS Studio after adding your cameras and the OBS Virtual Camera
1. Click the GEAR (settings) next to the OBS Virtual Camera in OBS
2. Select Output Type as Source and Output Selection as the Camera (in my case HD Pro Webcam) - click ok to save
3. Now Click to Start OBS Virtual Camera
In ZOOM
4. Configure the Video Settings
5. Select the OBS Virtual Camera
Done
Now you can use OBS to control the camera in ZOOM. This is excellent for PTZ Cameras
Thanks