Use ESP32 for bluetooth presence detection

HI all, I bought several ESP32 ATOM Lite modules which I plan to install at strategic locations across our house/garden for more accurate (room) Bluetooth presence detection of our phones. I setup first ESP module with default settings, only configuring my wifi credentials. In HA I now see the ESP with 1 entity (button.safe_mode_boot). What should I do next to get presence tracking of our mobile phones working?

Thanks!