How can I program a textbox so that when I double-click it, I fill it in with BD information?

Recently I got involved in a project and I have a doubt, if it is possible (and if it is how?) to be able to program a textbox that when writing an information and giving it double click on that same textbox auto complete the information referring to the database of other textbox .

Example:

I have two textbox , one for IDAlumno and one for Name .

In one I put the IDAlumno , having finished writing that ID and when I double-clicked it, I completed the textbox of Name , with the name of the person referring to that ID

The code is like this, create for the autocomplete

Sub autocompletarTextbox(ByVal campoTexto As TextBox)
    Try
        conexion.Open()
        comando = New SqlCommand("SELECT IDAlumno from Alumno", conexion)
        respuesta = comando.ExecuteReader()
        While respuesta.Read
            campoTexto.AutoCompleteCustomSource.Add(respuesta.Item("IDAlumno"))

        End While
        respuesta.Close()
    Catch ex As Exception

    End Try

End Sub 

and in the load simply call the function passing as parameter my textbox

autocompleteTextbox (CountNumber)