I can virtually guarantee Siri and your iPhone is not doing this. Apple would never allow it. It might be possible that advertising plugins on your web pages i

I can virtually guarantee Siri and your iPhone is not doing this. Apple would never allow it. It might be possible that advertising plugins on your web pages is using the microphone, but you need to have authorized this on the iPhone. If you didn't I'm inclined to guess it's just pure happenstance that similar ads appeared near to your conversations. But if I'm wrong, this would be easy to test. What are the web sites you've noticed this on? We could both go to that site and start saying specific phrases to see if we start getting ads that match them.