First of all open pdf escape website. upload your pdf to pdf escape and click upload.
After upload selects the particular checkbox and right-clicks and unlocks form field.
Again click the checkbox and right-click you will get the "object properties".
Click "object properties".
Next, You will get pop like "form field properties".
Here you will get "Export Value" - for example, Yes or 1 or 0
In your code use, this "export value" you will get output.