Combine the meatballs, apple cider vinegar, maple syrup, brown sugar and chopped apples into a slow cooker.
Cook on medium heat for 4 hours.
Reduce heat to low to keep warm and to let the meatballs soak up additional juices.
Skewer the meatballs with an apple chunk and drizzle with additional brown sugar to taste or serve them straight from the slow cooker to keep warm as well.