Retrieve Continuous Touch Coordinate

I want to retrieve continuous mouse position for my game requirement. At present I am using this code but it give point in some distance.

 myCamera.ScreenToWorldPoint(Input.mousePosition);

I want move precise point in output rather than following one.

Please give some suggestion in this. I already tried various camera methods but didn't get desire result.

If I have to use any specific algorithm then please give some detail on that also.