Have a grab state, since it is player can be a global variable I suppose, a bool isGrab
Player on collision with bar and isGrab=false, set isGrab to true
On down key pressed and isGrab=true, set isGrab to false
if isGrab is true, set player Y to ?, where ? is some value that makes it look like you are hanging from the bar
Don't use pin, you can't move with pin...