In the script add the following
private var listData:ArrayCollection = new ArrayCollection(
[{label:"Arun Kumar", data:"3"},
{label:"John Jose", data:"1"},
{label:"Mary Dam", data:"2"}]);
private function getSelectedCaree(event:Event):void
{
trace(event.currentTarget.selectedItem.data);
}
In the MXML add the following to show the combo-box with change event
mx:ComboBox id="comboList" change="getSelectedCaree(event)" fontSize="15" x="1000" y="50" dataProvider="{listData}"
/mx:ComboBox