Hey Amit. Your phone probably is not secretly listening for ads, but the ad industry has so many other signals that it often feels that way.
Ads are usually driven by your searches, location history, app usage, online purchases or loyalty card data, and who you are near or message, and your conversations often nudge those behaviors so the timing seems spooky. Big platforms publicly say they do not use the microphone for ad targeting and independent tests have not found consistent evidence, though a few shady apps have tried things like TV audio recognition in the past.
Modern iOS and Android also show a mic indicator when audio is captured and block background access unless you granted it. So it is likely coincidence powered by data collection, but you can still tighten settings to be safe.
On iPhone, go to Settings > Privacy & Security > Microphone and turn it off for any app that does not truly need it, then check Settings > Privacy & Security > App Privacy Report to see which apps used the mic and when.
In Settings > Privacy & Security > Tracking, switch off Allow Apps to Request to Track, and in Settings > Privacy & Security > Apple Advertising, turn off Personalized Ads.
If you do not need hotword listening, disable Listen for Hey Siri in Settings > Siri & Search, and watch for the orange mic dot at the top of the screen.
On Android, open Settings > Privacy > Permission manager > Microphone and revoke it for unnecessary apps, check Settings > Privacy > Privacy Dashboard > Microphone to see recent access, and in Settings > Google > Ads choose Delete advertising ID or Opt out of Ads Personalization depending on your version.
You can also disable the hotword in Settings > Google > Settings for Google apps > Search, Assistant and Voice > Voice > Voice Match, and Android will show a green mic indicator when anything is listening.
