37-year-old Simpson resigned from his role as Dale manager at the end of the season, and has been training with the Brunton Park CLub with a view to a permanent deal.
Carlisle manager Roddy Collins reckons that Simpson can play a key role in the heart of midfield.
He said: "Paul is from Carlisle and is very keen to come and play for us.
"He can play on the left and right of midfield, is very experienced and would be a good addition to our squad."