I got this to work quickly using this code:
For a quick test:
pip install spidev
change line 6 in IMU.py to
imu = MPU9250(spi_bus_number = 5, spi_dev_number = 1)
and run python IMU.py
will output the sensor values until you abort
e.g.
Acc: -0.006 +0.081 +0.990 Gyr: +2.317 +1.098 +0.854 Mag: +37.691 +14.026 +21.0451