Find Objects in combobox WPF

I have a combobox filled with a list of objects itemAttributes that is defined as 

01 value-id pic 99999999 value 0 property as "ID".
01 attribute-value pic x(30) value spaces property as "VALUE".

im triying to find the index of the object inside the combobox by its ID property but i cant manage to figure it out.

something like this

set cbAttrib1::SelectedIndex to cbAttrib1::Items::IndexOf(valueID)