Extracting Hounsfield units of segmentation


I have segmentation of the series of DICOM images (I have those images as well). I would like to output spatial coordinates of the segmentation (just lik in STL format) as well as Hounsfield units at those points.
Simply put, I want an output with 4 columns: first three entries are XYZ coordinates and the fourth column is the value of HU at that location.

XYZ coordinates of the segmentation can be simply obtained by saving closed surface to the STL file. But how to get out the hounsfield units I cannot figure out.

I understand that if the cloud point is in between the slices, then HU values has to be interpolated - thats is fine.

Any advice?

Note: I’m very new to the Slicer.