Which type of rocks are mainly found in caves?

More accurately I think you mean "What type of rocks hold caves?"

The majority of caves are in Limestone; some in its metamorphic edition, Marble. These, "karst" caves, often also hold calcite deposits (stalactites etc) formed by precipitation of the calcium carbonate dissolved from the rock above the cave by the water oozing through its joints.

There are also lava tubes in basalt lava, formed by molten rock flowing from below a solidified crust.

Sea-caves and mass-movement fissures can occur in most competant rocks.