There is the Tilemap.positionToTileX(xcoordinate) and Tilemap.positionToTileY(ycoordinate) for retrieving the tile X and Y. And there is the Tilemap.tileAt(tilex,tiley) to get the ID. If the ID is -1, then no tile exists at that location.
You can check if a point overlaps with a Tilemap in the system expressions, and use the point's coordinates to get the tileX,tileY , and then from those the ID. That way, you'll be able to check collisions based upon the tile ID.