Hi @x_nerve,
thank you for reaching out to us. The most straightforward way to sample a FieldObject is FieldObject.Sample; there are also other sample methods attached to the various fields related classes, most notably c4d.FieldList. We have two examples in the Python SDK examples which showcase field sampling, fieldlist_sampling_r20 and fieldobject_sampling_20.
You also mention "Is there a way to get the weight of the cube field points?"; you are probably aware of this, but since your phrasing could imply otherwise, it seems noteworthy to point out that fields are not discrete. So in other words, there is no finite amount of points you can exhaustively sample for a field object, since the object is non-discrete. You have to pick a point or a set of points you want to sample for a field object, which can be any point in in the value range c4d.Vector can handle.
If there are any questions left, please do not hesitate to ask.
Cheers,
Ferdinand