Reggie Lambe came on in the 45th minute as Carlisle suffered their first league defeat of the season after they were shocked 2-0 at League Two strugglers Newport.
Keith Curle's team entered the game as the only Football League side who had not lost this season but goals from Josh Sheehan and Rhys Healey put an end to that run.
Swansea loanee Sheehan opened the scoring with a drilled strike just two minutes in after Carlisle failed to clear Jazzi Barnum-Bobb's low cross.
County then sat back as Carlisle pushed for an immediate reply, with Macauley Gillesphey blasting a shot wide before Jabo Ibehre volleyed over the crossbar.
After the interval, the Cumbrian outfit grew frustrated as they failed to penetrate a resurgent County wall.
Their woes were capped off in the 72nd minute when Dan Butler collected Josh O'Hanlon's clearance and the defender teed up Healey, who coolly slotted the ball past Mark Gillespie into the bottom left corner.
