Noble had already hit a post within seconds of coming on in the 85th minute, and a mistake by the home defence handed him a chance to finish them off.
Walsall took the lead with a flowing move in the 18th minute. Florent Cuvelier sent in a low cross, George Bowerman dummied over it and Jamie Paterson drove in his second of the season with a right foot shot.
But Carlisle soon began to show their quality and, after Karl Darlow saved from the lively Danny Cadamarteri and Matt Robson shot wide from a good position, they equalised in the 29th minute.
Referee Carl Boyeson waved play on when United were demanding a free kick, and Kallum Higginbotham then crossed a beauty which Joe Garner headed in from close range - his first goal since returning to his old club on loan from Watford.
In the second half Walsall's top scorer Bowerman missed a good chance to restore the lead, and an impressive Carlisle made the Saddlers pay.