This low-bulk bracing is used by sports trainers and wilderness medics to stabilize weak ligaments and discourage further injury. You can apply all sorts of extras like pre-wrap liners, ankle pads, and skin adhesive, but here's the down and dirty trail version.
This method is popular with ultralight thru-hikers and requires two materials that you don't normally carry (cord and carabiner). Like all bag hangs, it can be foiled by smart, food-conditioned bruins. Check regulations to make sure bag hangs are legal.