Uses the WeMos D1 board (full size) and a DHT22 thermo-hygrometer sensor. The boards are available all over the internet:
Amazon's choice for the WeMos D1 (is actually D1 R2)
https://www.amazon.com/dp/B01C6Y5SKY
Amazon's choice for the DHT22
https://www.amazon.com/dp/B0795F19W6
Amazon's choice for breadboard jumpers
https://www.amazon.com/dp/B01L5UKAPI
Connect the DHT22 + to a 3.3V pin
Connect the DHT22 - to a GND pin
Connect the DHT22 data to pin 8 on the D1 board
Create a free account on https://cayenne.mydevices.com
Add a new device and record the username, password, and clientID
Substitute it in the proper location in the code
Add the ESP8266 board to the Arduino IDE.
Use the board library esp8266 from http://arduino.esp8266.com/stable/package_esp8266com_index.json
Select the board from Tools/Board/Board Manager
Set the board options to:
Board: WeMos D1 R1 Upload speed: 115200 CPU freq: 80 MHz Flash size: 4M (3M SPIFFS) Upload using: Serial
You'll need these libraries (Tools/Manage Libraries):
WiFi (Built-In) CayenneMQTT DHT sensor library Adafruit Unified Sensor
Enter your wifi SSID & wifiPassword into the code
Push to the device using the Arduino IDE