How might I rotate virtual camera (orb transposer) around a screen point.

I'm going for the camera behavior very similar to pokemon go.

Below is a snapshot of how my current camera setup looks. So far everything looks good but, I wasn't entirely sure how to map the rotation on to the Mouse X.

Current CameraControllerCode

Code (CSharp):

1. void Start(){
2.     CinemachineCore.GetInputAxis = GetInputAxisHandler;
3. }
4.  
5. public float GetInputAxisHandler(string axisName)
6. {
7.     if(axisName == "Mouse X")
8.     {
9.         if (Input.GetMouseButton(0) || Input.touchCount > 0){
10.             // not correct behavior as it just spins the camera as I move mouse from left to right
11.             return (Input.touchCount > 0) ? Input.touches[0].deltaPosition.x : Input.GetAxis("Mouse X");
12.         }
13.         return 0;
14.     }
15. }