I have created a chatbot with IBM Watson Assistant. But currently I have hardcoded all values in the dialog e.g : When some user will ask "Who created Computer ?" then in the dialog flow I have written "XYZ created computer".
But suppose the user will ask about some other person and that value is not hardcoded in the dialogs on IBM Watson Assistant then is there any way by which I can provide Google search results?
You can make programmatic calls from within IBM Watson Assistant dialog nodes. Both server-side actions (IBM Cloud Functions) or client side calls (within the app) are supported. That way you can react to such queries as described and could call a search engine, database or somethin else.
This IBM Cloud solution tutorial on how to build a database-driven Slackbot uses server side actions to interact with a Db2 database. Instead of calling out to a database to fetch data, in your example, you would open a request to Google search.
I saw that you tagged it "facebook-apps". If you use Botkit middleware to build an integration with Facebook Messenger, then check out this blog on how to enable actions in the Botkit Middleware for Watson Assistant.