Preheat oven to 350 degrees. Line a baking sheet with aluminum foil.
Trim about 1 inch from one side of each pita pocket and arrange onto prepared sheet.
Roll sausage into 32 small meatballs.
Heat a large skillet over medium heat. Fry meatballs in skillet until completely browned on all sides, about 5 minutes. Drain meatballs on a plate lined with paper towel.
Stir pasta sauce, onion, and cream cheese together in a saucepan over medium heat; cook, stirring regularly until onion is tender, 7 to 10 minutes.
Transfer meatballs to a large mixing bowl; add 1 cup of the pasta sauce mixture and mozzarella cheese. Mix until the meatballs are coated in sauce and cheese.
Gently stuff pita pockets with meatball mixture using a small spoon.
Bake stuffed pita pockets in preheated oven until heated through and the cheese is melted, about 10 minutes.