My monitor has a headphone jack in the back. Can I use it only sometimes without having to plug/unplug it?

I would occasionally like to use (wired) headphones, but 90% of the time I am fine with just hearing the audio that comes out of the crappy monitor speakers. If I plug the 3.5mm cable into the monitor's headphone jack (even without headphones attached), then no audio will come out of the speaker anymore....