The 24-year-old is out of contract this summer and can move on a free transfer after playing a minor role in Ian Holloway's side clinching promotion to Division One next term.
Carlisle has had a difficult season after needing treatment for an alcohol-related illness back in September before being the subject of a reported January transfer move to relegated Premiership side Leeds United.
Following The Blades' failure to reach the First Division play-offs this term, Warnock has been told to look for free transfers in order to build a side that can clinch promotion to The Premiership.
It remains to be seen if Carlisle will be moving north to the South Yorkshire outfit, as QPR have yet to decide who will be staying or leaving Loftus Road this summer.