We propose a new method to fabricate a nanocantilever with a mechanical oscillating ball on its end. The method is based on local electrochemical etching in a very thin electrolyte liquid layer. It allows fabrication of a very sharp tip as well as a ball tip that can be used in dynamic mode control of atomic force microscopy. The oscillating part measures 50 nm in diameter; the diameter of the ball tip is 1.5 mu m. Because of the small mass of the oscillating ball and the small size of the threadlike neck, the estimated resonance frequency is around 300 MHz. This technique will help to increase the force gradient sensitivity in dynamic mode control of atomic force microscopy.