Nonsense sounds in the mesa biome

I’m hearing a sound that is like construction workers working but when I got to the place with the sound, I couldn’t hear it anymore. But then, when I went away, I heard the sound again. I was in the mesa biome and the sound was coming from the middle of one of the mountains. The sound was not any of the mobs I know. But, in the middle of the mountain, was a cave. It went for about 5 minecraft miles. But sorry. I was so scared that I deleted the world before I had time to take a screenshot.