You don’t need to get too technical to keep the kids amused but you should aim at raising their curiosity level. Even with all the computer games in the world kids still love the unknown and a challenge.
Once we made a little treasure box of goodies for example with trinkets and gold chocolate coins and lots of cheap novelty toys. We then buried it (use mostly sand for the burying part) and then copied an old map off the net which we printed and stained with tea and burnt the edges to make it look old.
Of course the kids couldn’t resist finding the treasure once they “found” the map and it was a great success (although some kids did wonder why the gold nuggets had paint that came off)
Kids have lots of technical equipment these days but they are still kids deep down inside