Check out this thread: How I Monitor my Sump Pump
I have some images of my setup with the leak sensor (with a lead) strapped to the pipe inside the pit.
Any leak sensor with a lead would work, I was going to use this ecolink one but they were hard to find at the time: https://www.amazon.com/Ecolink-Zwave-Freeze-Sensor-FLF-ZWAVE5-ECO/dp/B0716YVPLG/ref=asc_df_B0716YVPLG
The one I used is a "NEO Coolcam" brand from Ali Express, they also make a Zigbee version which some people on this forum I have seen mention as well. Mine is on the original battery from a while ago and still showing 90%.
