Eastern NC BBQ sauce is at heart an extremely simple thing. Most who talk about 'secret ingredients' are just BSing. I won't give you an exact recipe because it really is something you'll want to play with to your own tastes. A lot of people who don't grow up with this type of barbecue might find such a strong vinegar flavor over powering.
At its base it is: apple cider vinegar, salt, cayenne, red pepper flakes and black pepper. You might want to add water to dilute it a bit and there are other things like lemon juice, wooster, hot sauce, paprika, brown/white sugar or molasses, celery seeds, onion & garlic powder etc to mix it up with. It's well known many BBQ joints enjoy a little MSG here and there, if you have fish sauce you could even throw a tiny bit in for that extra umami. That's it though. Whisk it in a bowl, adjust levels to your taste and then store for a day and taste again.
If you want to play with it further - and straight vinegar is a little harsh to your palate - another variant found in central NC is basically the same but with the addition of ketchup and/or yellow mustard (always more ketchup than mustard), thrown in a pan and let to simmer for a few minutes to dissolve. Since you're heating that up, you could play with small amounts of aromatics like clove or star anise to mix it up more.
It's nothing set in stone though. Have fun with it!