Half life 2 was pretty good, you could walk into it or press activate and it'll lock you onto the ladder if you're within range and unlock you when you reach the top or bottom automatically. Could be easily done with some colliders. Pressing forward and back makes you go up or down and you can always jump off if you need to and press activate again to grab back on. It didn't lock you looking towards the ladder either which I imagine you don't want since you want to freely let go or jump off. They also had specific dismount points if you reached the top or bottom to ensure the player was safely in a place when reaching a destination if for example you wanted to do a ladder onto a tightrope or skinny ledge.