Modular user-exchangeable accessory for bio-signal controlled mechanism. In some embodiments, a biosensor and a feedback mechanism is disclosed. In some embodiments, a modular user-exchangeable accessory for bio-signal controlled mechanism includes detecting bio-signal using a bio-sensor and sending a control signal to a modular user-exchangeable accessory for bio-signal controlled mechanism. In some embodiments, the biosensor is connected to a headset, wherein the modular user-exchangeable accessory is attachable to the headset. In some embodiments, the modular user-exchangeable accessory is shaped to resemble an animal ear.