Nothing in the hole. It looks like whatever (”phone clip?”) was in the hole was removed, and possibly forcefully. So my plan at the moment is that some day, when I feel like moving the dresser and the night stand (solid wood and very heavy), I’ll watch a video to refresh my memory, then take notes as I remove the jack from the bedroom and put it into the living room.
Hole sliding and wire stretching are tedious and thankless tasks.