Hi Venkata,

I guess you want to leverage Captcha functionality apart from login, 

During my research, I found a very useful design implementation.

High level step below to include Captcha in custom flow action.

• pyGenerateCaptcha activity is used to generate Captcha image OOTB
  • Basically it generates and sends captcha Image to browser and populates property pzCaptchaAnswer property with the generated image text
  • Customize pyGenerateCaptcha activity to populate the desired property on a Page

• Create a section to use HTML rule (which will contain captcha code)
  • "<pega:include name="Captcha" type="RULE-OBJ-HTML"/>"

• In HTML rule use the following snippet to show
  • 

• Use the section directly in you flow action's main section with a Input field to enter captcha text

• You can validate in Flow action validate

Here is the final output

Hope it helps you in implementation. Kindly notify if it helps you in implementation.