Sensor Fusion LiDAR and RADAR

How to do sensor fusion of LiDAR and RADAR data? I wanted to track the object, position and velocity. LiDAR are good for position estimation and RADAR are good for velocity estimation, hence I wanted to fuse these data.

That depends on what approach you choose.
You could take a look at:

Note that a lot of people use fusion methods on nuScenes, but we don’t provide any code for it.