Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from Cagayan de Oro to Dammam as you normally would.
These are just IATA (International Air Transport Association) codes. They are used in aviation to identify and differentiate airports. That’s why a Cagayan de Oro Laguindingan Airport to Dammam King Fahad Intl Airport flight would often be abbreviated as a CGY to DMM flight.