Wash and dry the apples thoroughly. Insert lollipop sticks into the top of each apple.
In a medium saucepan, combine sugar, corn syrup, and water. Cook over medium heat, stirring constantly, until the sugar dissolves and the mixture comes to a boil.
Continue to boil, without stirring, until the mixture reaches 290°F (hard-crack stage) on a candy thermometer.
Remove from heat and stir in vanilla extract. Carefully dip each apple into the candy mixture, coating completely.
Place the coated apples on wax paper to cool and set completely.
Once set, melt the candy melts according to package directions. Dip the apples into the melted candy, then into the sprinkles.
Notes
Store candy apples in an airtight container at room temperature for up to 3 days.