Get the value from the \Fill-In\" option of the Choice Control-Checkbox"

I have a coice-Checkbox control, where I have selected the "Allow 'Fill-in' choices" as Yes. This gives the user the option to specify a value not already in the options.

Now, my requirement is to capture the value entered by the user.

Could somebody please suggest a solution, both -

1) Out of the box, and

2) using JavaScript

All responses are appreciated.

Thanks.