In current time this device is wildly used for school and college project because it is easily programmable via Arduino IDE Software and it is very cheap in price. Using Nodemcu and relay you can make your own Smart home device.
Here is the full tutorial video by IndianLifeHacker. which help you to make Own smart home devices using NodeMCU, relay and some jumper cables.
NodeMcu ESP8266 WIFI Development Board: https://www.flyrobo.in/nodemcu_esp8266_wifi_development_board/
5V Single Channel RELAY MODULE: https://www.flyrobo.in/5v_single_channel_relay_module/