A wearable device for a noninvasive measurement of a user's body temperature can include a housing, a first substrate coupled to the housing and having an opening, a second substrate coupled to the first substrate and configured to secure to skin of a user, a mounting frame enclosed by the housing and the first substrate, a circuit board secured by the mounting frame, a temperature sensor coupled to the circuit board and configured to determine a body temperature of the user, and a thermally conductive probe. The thermally conductive probe is secured by the mounting frame and positioned proximate to the first temperature sensor. The thermally conductive probe extends at least partially through the opening in the first substrate and transmits a thermal energy from a portion of the user's skin to the first temperature sensor.