You don't need cable ties. We've traveled all over the world and have never needed them.
When your check your bags at the airport, they will go through an x-ray machine. If they see something that looks suspicious, they will unlock your luggage locks and check it out. They will lock them when they're done. Just make sure you don't put anything of any value (like a computer, camera, etc.) in your suitcase.
You will go through airport security and that will include a metal detector and/or a scanner. The only time they will personally search you is if you have something on you that would set it off. Just make sure you put everything in your purse or backpack and don't carry items that are not allowed, such as a knife.
When you check in at the pier for your cruise, your luggage will again go through an x-ray machine. If they see something that is questionable, they will not open your bags, but will ask you to come down and open it in front of them. And as with the airport, you and your carry-on luggage will go through scanners, but again, you will not be personally searched unless you set the machine off.
Talk with your agent and they can provide more exact information and answer any of your questions you may have.