Odoo IoT Box supports the Bluetooth caliper. If you want to take measurements in your module, you can use the iot_take_measure_button widget to fetch them in Odoo. To do so, you will have to use the <widget> tag, as shown in the following code. Note that like iot_picture, here you will also need to add the ip and identifier invisible fields in the form view:

<widget name="iot_take_measure_button"
        options="{'ip_field': 'ip', 
                  'identifier_field': 'identifier',
                   'measure_field': 'measure'}"/>