Who do I make a archeology block, like a suspicious sand

I'm not entirely sure how you would do a sort of sustained-right-click system like the vanilla suspicious blocks; the way I implemented this was by just having a right click convert the block to a new state, (By replacing the block with a new, more dug-out block), and then having the player try to remove as much of the block as possible without going over. (More similar to the demo version of archeology.) If you want to do a repeated right-click thing, it's as simple as just replacing the blocks, and then using a /loot command to drop a random item from any of your loot tables. 

Presumably, the sustained-right-click system is possible, but you'd have to take a look at the vanilla code. (If you navigate to the file manager in the left side of the workspace, you can find it somewhere in external libraries/gradle forge 1.20.1/net/minecraft/world.)