The article I linked to references the original findings. Apple wasn’t caught, they were exposed by a whistleblower. I’m not as familiar with the cases involving Alexa and Google Assistant but those incidents are also referenced in that article.
The gyroscope and accelerometer can be used to capture poor quality audio. I’m unsure if those are the only components which can be turned into microphones. Again, this is not something you should expect from any malware. I’d only expect this to be used on high-value targets.