I'd say turn the car upside down and shake it but then all the fluids would run all over. Sorry, looks like you will need to remove the timing chain cover. It can be done leaving the head and oil pan in place if you take your time and be careful when you put it back on.
This sounds reminiscent of my first valve adjustment when the adjuster wrench clattered down the hole. I used a strong magnet on a stiff piece of wire and extracted it fairly quickly. Another idea would be to get one of those long tools that has 3 or 4 fingers on the end of it, and when you reach the piece you need to extract, you slide the body of the tool forward which tightens the fingers around the object. SORRY, I cant remember what that tool is called. The downside is , you have to be able to see the bolt. GOOD LUCK!!!!
You can first remove the oil pan. The bolt hopefully dropped past the lower chain gear and into the oil pan where it can be removed. If so, then you probably can't get to it with the magnet.
If you remove the oil pan, then all you have to do is bolt it back up instead of removing the front cover and all the bolt-on things around it. I hate having to put that oil pump back in and see if it is timed right.
If you don't find the bolt in the oil pan, then you have more light on the bottom area of the front cover. Use a flashlight to try to see in there and use some other tools mentioned above to find and remove the bolt.