The probe is an optional attachment for the leak sensor.
Wyze Sense Leak Sensor Probe is an attachment for Wyze Sense Leak Sensor. It helps to wrap around to places that are hard to reach, like underneath a dishwasher or in a crawlspace. The probe cannot work independently, and must be attached to a leak sensor to function.
Wyze Sense Leak Sensor is the main device and can work independently, without a probe.