The sound coming out of the speaker will then go back into your microphone, causing distortion and echo.
Using a pair of headphones/microphone should clear that problem, wired or wireless. I use a pair of Bht200 wireless earbuds perfectly with my phone and PC.
ZOOM (and Whats App, Messenger, Skype etc) however usually needs a camera which can have the mic built in. Make sure you are using the headphone mic and not the camera one.