Need help with the interaction entity

Hello. I want to make a datapack that works with my resource pack. It's a lightsaber resource pack where I have a lightsaber on any sword and I have a version that is set to off on a stick. Now I would like to make the lightsaber turn on/off by making functions that summons a interaction entity that teleports around the player so I can replace the item in the main hand and when the item is not in the main hand that the interaction entity will be gone. I also want this to work so I can add this to many different lightsabers but I do not have a lot of knowledge with these things.