Instructions
Obtain a gun with a long firing range, such as a rifle. In the "Zombies" levels of "Call of Duty: World at War" guns are hanging on walls all throughout the level. Walk up to a gun and press "Square" to purchase it and add it to your inventory.
Walk around the level until you find the area with the tall, barred metal gate. The gate itself is much taller than your on-screen character. It is the only barred metal gate in the entire level. Walk directly up to the metal gate and look through it -- the "Fly Trap" can be seen off in the distance affixed to a wall.
Press the "L1" button to look down the sights of your rifle. Use the right analog stick to line up the "Fly Trap" in your sights. Press "R1" button to fire. You may have to fire a few times as the "Fly Trap" is a great distance away from your character. When you successfully shoot the trap, it will be activated. A message will appear on screen indicating that you've unlocked the "Elevate your Senses" trophy.