How can we track Facebook Campaign Clicks through Google Analytics ?

You need to tag your Facebook campaigns. Campaign tagging means adding parameters to the end of your landing page URL to identify the source. You get the details about creating custom campaigns from here https://support.google.com/analytics/answer/1033863?hl=en

Generate custom campaign parameters for your advertising URLs.

When you have a URL in your ad, for example, in a web ad or in an email, you can add parameters to that URL in order to capture important reporting data about your campaign like the site on which the ad appeared, the campaign name, and keywords you used in the ad. A URL with these kinds of parameters looks something like:

http://www.example.com/?utm_source=adsite&utm_campaign=adcampaign&utm_term=adkeyword

https://support.google.com/analytics/answer/1033867?hl=en