As for now, it is not possible to associate a product with a campaign, however in the nearest version of the application, most likely in 7.14.1, the campaign designer will have 2 new elements - 'read' and 'add' data elements, the same as in the business processes. With their help, you will be able to create products upon some certain conditions, for example if a user clicks on some link, the product would be automatically created, etc.
Thanks for the information !! Also one more query, Is there any way in which one campaign can be connected to another and any way one campaign can be included in marketing plan?
Unfortunately, it would not be possible to associate the campaigns one to another since according to the application logic each campaign is unique. As for marketing plans, basically this section does not include the campaigns, however you can add a new lookup on a marketing plan or activity page, which is based on a Campaign object. It would indicate which campaign was started during the marketing plan.