Setting rotation but with an offset.

I'm currently making an object rotate around based on user input using the following code (a slightly modified bit of code from MouseOrbit:

    void HandleSwimRotate()
     {
         rotX += Input.GetAxis("Horizontal") * xRotSpeed * 0.02f;
         rotY -= Input.GetAxis("Vertical") * -yRotSpeed * 0.02f;
 
         rotY = ClampAngle(rotY, yRotMinLimit, yRotMaxLimit);
 
         var rotation = Quaternion.Euler(rotY, rotX, 0);
 
         transform.rotation = rotation;
     }

This works as expected, but the center of the object (a humanoid character) is at it's feet. I would like to rotate the player around it's center. Is there anyway to set the rotation with an offset without changing the center point?