Add additional option to combobox in powerapps

Suppose you have a collection col_AllEmployeeResults & you are showing Title & Email fields in combobox. You want an additional Select option to show in the combobox. Put below in the Items property:

Ungroup(

    Table(

        {items: Table({Title: "Select", Email: "Select"})},

        {items: ShowColumns(Filter(col_AllEmployeeResults, IsActive <> false), "Title", "Email")}

    ),

    "items"

)