Can i specify which slot the player needs to have an item in for the event to trigger?

I'm trying to make a jet pack, so I was trying to make a key binding that when you press space you will get levitation, but I wanted it to only trigger when the player is wearing the jetpack, I found a thing in the procedure so I could make the player get levitation when the player has the jet pack in his inventory, but I didn't find anything that made the player only get levitation while actually wearing the  armor, and not just having it in their inventory. please help... how can I specify which slot the player needs to have the jetpack in?