A micro speaker is disclosed. The micro speaker includes a vibration system including a diaphragm and a voice coil for driving the diaphragm, the diaphragm including a conductive dome and a suspension surrounding the conductive dome; a magnetic circuit system including a lower plate, a first magnetic part on the lower plate, a second magnetic part on the lower plate, a pole plate attached to the first magnetic part, one of the first and second magnetic part being a permanent magnet for forming a magnetic gap. The conductive dome includes a number of units for forming capacitors together with the pole plate for outputting electrical signals according to vibrations of the diaphragm and for detecting real-time replacement of the diaphragm.