Try to distract the orcs
Orcs are really strong and tough, but they’re not very clever. If you can distract them then you could sneak over and grab the sack without them noticing.
But how will you do it? You look around for something you could use to help you. There’s a pile of old junk behind one of the boulders. You search through it and find a bag of marbles and a packet of cotton wool balls.