How to acquire data from the username & password fields in Okta Signin Widget

I’d like to use the Okta signin widget for both SSO sign on and username/password sign on in my React application. When selecting the “LOGIN” button, I’d like to be able to intercept the call to Okta and grab the username and password and send them to my own login in instances when I’m not using SSO. Is there a way to:

1 - intercept the handler for the LOGIN button and/or
2 - acquire the data from the username and password fields to use myself

I’ve seen instances in other applications where there are bottons that say: LOGIN with SSO OR Login using but they use the same input fields. How do they do this?