The closest I can get to what you want is if I use a ValueMember for the index. For example:
I fill my Combobox with a couple of Items like this:
Public Class NameValue
Property Name as String
Property Type as Integer
Public Sub New(ByVal pName as String, ByVal pVal as Integer)
Name = pName
Type = pValue
End Sub
End Class
Dim cmbList As New List(Of NameValue)
cmbList.Add(New NameValue("Name",1)
cmbList.Add(New NameValue("Name2",2)
cmbList.Add(New NameValue("Name3",3)
cmbType.Items = cmbList
cmbType.ValueMember = "Value"
cmbType.DisplayMember = "Type"
Now the first stage is complete. The Combobox contains three items with a name and a value bound together. Next step is to setup what you are asking for: Bind the ComboboxValue to the Object class.
cmbType.DataBindings.Add(New Binding("SelectedValue", BindingSourceName, "Type", False, DataSourceUpdateMode.OnPropertyChanged))
As soon as the BindingSource "BindingSourceName.DataSource" changes, the combobox should be updated. And if you change the combobox, the Object.Type will change to the selected Value.