Karl Hawley had Scunthorpe's best chance of the first half when he battled his way past Matty Robson to create a shooting position as he closed in on goal, but his effort flew harmlessly wide.
Goalmouth action was limited in a scrappy game although Jimmy Ryan's first-time shot from Mark Duffy's free-kick and a powerful Tom Newey header from another Duffy set-piece had the Carlisle defence under threat.
Carlisle found it hard to prise open a tight Iron rearguard although Andy Welsh, making his first start of the season, produced one promising break only to finish weakly with a low shot straight at goalkeeper Sam Slocombe.
The home side started the second half with greater energy and Sean O'Hanlon's header tested Slocombe, but it was Scunthorpe who took a 52nd-minute lead when Newey made progress on the right before drilling a low ball across the six yard box where Hawley was on hand to apply the finish.
Carlisle's teenage substitute Symington had only been on the pitch three minutes when he drew Carlisle level with a blistering 30-yard free-kick, which gave Slocombe no chance as it tore into the roof of the net.