You could use this: https://sensysmagnetometer.com/products/magdrone-r4-magnetometer-for-drone/ https://sensysmagnetometer.com/products/magdrone-r4-magnetom...

You could use this: https://sensysmagnetometer.com/products/magdrone-r4-magnetometer-for-drone/ https://sensysmagnetometer.com/products/magdrone-r4-magnetom... We have the little version of this sensor. It's quite interesting.