Exposing the Hair Shading Anisotropic Gradient into a node

Greetings from my side to you,

I’d like to know if anyone here has an idea on how to expose the Anisotropic Gradient (that wide spec highlight) to a note that could be used in the material graph of any kind of material shading model.
Or alternatively: How could I calculate this Gradient inside the “Custom” Node of the Material Editor.

Greetings RRe36