http://cjoint.com/?ftgD2c3vVQ

In module:

Function ColorBack(c As Range)
Application.Volatile
ColorBack = c.Interior.ColorIndex
End Function

In C2: =ColorBack(B2)

A B C
1 Name Salary ColorBack
2 Goutte 4900 6
3 Miroux 4500 6
4 Martin 4000 36
5 Zorba 3200 36
6 Dupont 4000 37
7 Merino 4000 37

Cordialy JB