MQTT with Subscribe to broker on Internet

Can anyone guide me to a working example. I want to use mqtt on esp8266 and I want to subscribe to a broker on Internet (I already use it from a raspberry pi ). I have tried many different examples, but mostly they only publish or otherwise use ethernet.

Finally I also will connect to 1306 oled for presentation.

Have you tried the standard MQTT example for ESP8266 (pubsubclient/examples/mqtt_esp8266 at master · knolleary/pubsubclient · GitHub)
It does what it should.