Data transfer from ARDUINO to PIXHAWK through serial or I2C

I have 4 analog sensors. I have read the analog output of all sensors using Arduino Uno. now I want to write all sensor data using I2C protocol into another microcontroller that also has I2C.

This means I read analog sensor output and write this data into Pixhawk I2C port.

Can anyone guide me on how can I write sensor data into the Pixhawk I2C port and view this data in the mission planner?