customsensor.yaml

esphome:
  name: foobar
  platform: ESP8266
  board: d1_mini
  includes:
    - "Foobar.h"

sensor:
- platform: custom
  lambda: |-
    auto mysensor = new Foobar(1000);
    App.register_component(mysensor);
    return {mysensor};

  sensors:
    name: "foobar"
    unit_of_measurement: foos
    accuracy_decimals: 1