A removable wearable device sleeve includes a sleeve body, one or more sensors, and an interface for operative communication with the wearable device. A removable sleeve includes a sleeve body having a front element having a first aperture, a back element having a second aperture, a tubular element having a first end and a second end with a third aperture, and one or more back elements define a cavity to encase an earpiece, an interface, and a sensor, wherein the sensor communicates sensor readings to the wearable device through the interface. A method of placing a sensor configured to communicate with a wearable device onto the wearable device includes providing a removable sleeve and inserting the wearable device through the first aperture of the front element into the cavity of the removable sleeve to provide a removable wearable device sleeve.
