I don't know which drone you have. I have the mini and I have had it apart at least 3 times from crashing it and there is not much metal for a magnet to grab onto, it's mostly plastic and solder. At any rate if you do get it back I have some tips on maybe getting it to work again. I learned this from boating. I know a couple guys that sunk their boats and they recovered the motors using what they called "pickling". This would be easier done with a small drone but the difference is that an outboard has fuses, I don't think the drone does. Without fuses you have power going to critical circuit boards and they probably will get fried. I recovered a cell phone once doing this but it only lasted about 6 months before dyeing. This may sound counter intuitive but if you get the AC to the surface keep it in water, scoop it out with a bucket and don't let it get to air. Remove the battery while keeping it underwater. Keep it in the bucket and keep shaking it in the water to try and get any mud and sediment out, do this for at least a couple days. Then get several gallons of distilled water, lower the water in the bucket by syphoning it off until the drone is just under water. Start adding the distilled water while still shaking the drone and syphoning it off, always keep the drone under the liquid, its the introduction of air to the water and drone that will kill it. When you have gone through 4 or 5 gallons of distilled water to replace the lake water, you now introduce alcohol. You want to use a commercial grade alcohol with no water, I think it's called 200 proof or 100%. The alcohol will eventually dry up the water. After you think most of the water is gone (This is all guess work) then you remove the drone from the alcohol and let it dry for about a week. GOOD LUCK