Spray 1 1/2-quart slow cooker with cooking spray. In slow cooker, mix pizza sauce, pepperoni, onions, bell pepper and olives.
Cover; cook on Low heat setting 3 to 4 hours.
Add mozzarella cheese and cream cheese to dip; stir until melted. Serve with vegetables. Dip can be held on Low heat setting up to 2 hours.