In a large bowl with a hand mixer or in the bowl of a stand mixer with the whisk attachment, whip together the cream cheese, whipped topping, vanilla, cake mix, and milk. Gently stir in the sprinkles.
8 ounces cream cheese, 8 ounces Cool Whip, 1/2 teaspoon vanilla extract, 5 tablespoons milk, 1 cup cake mix, 1/2 cup sprinkles