Distinctive for mining rather than cave.
If lower down the hillside the miners had driven a level (following a vein) and the vein had widened to form a workable lode, they may dig it out, upwards if that's where it was rich, and form a cavity/stope above the level as they work.
If the stope is tall enough and the miners knew they were nearing the surface even if the mineral was already worked out, they'd sometimes continue up to break surface and create an air shaft. Just like your photo, often a fairly small hole with no other surface sign of works around it. But a potentially deep and dangerous hole you don't want to fall down.
Can make an exciting entry point for an explore and trees to anchor your rope, but ranging somewhere between slightly sketchy and fatal, depending on how loose it all is... you don't want to accidentally bring a ton of boulders down on yourself from around the opening.
The place to look for evidence of mining would be lower down the hill