I am writing this answer so that others can get help in case some one else is facing this problem. First things first; you can't directly handle mouse move messages from Clistbox. So, you create a new class based on ClistBox class and then handle OnMouseMove() in that class.Then, inside that OnMouseMove() function you should get the item in the clistbox based on the mouse coordinates (as mentioned by IInspectable).
For code example; see below.
BOOL b;
int n = ItemFromPoint(point,b);
CString str;
GetText( n,str);
AfxMessageBox(str);
I guess similar solution should work for other controls like CButton etc.
Hope, this helps.