Hold Keybind

I don't know if this question has been asked but if so i can't find it.

I am wondering how to do a hold keybind. I am fairly new to mcreator and still learning the ropes.
My vision is that whenever I hold the key I get a specific potion effect and when released the effect will be gone.
I've tried to look for a way but to no avail.

Hope someone out there can help, thanks in advance.