You can use the Facebook pixel to track your website visitors’ actions. This is called conversion tracking. Tracked conversions appear in the Facebook Ads Manager and the Facebook Analytics dashboard, where they can be used to analyze the effectiveness of your conversion funnel and to calculate your return on ad investment. You can also use tracked conversions to define custom audiences for ad optimization and dynamic ad campaigns. Once you have defined custom audiences, we can use them to identify other Facebook users who are likely to convert and target them with your ads.

Sample:

fbq('track', 'Purchase',
  // begin parameter object data
  {
    value: 115.00,
    currency: 'USD',
    contents: [
      {
        id: 'homeowner',
        quantity: 1
      },
      {
        id: 'income',
        quantity: 344333
      }],
    content_type: 'product'
  }
  // end parameter object data
);

See this for details: Conversion Tracking with Custom Parameters

Reference of Supported Parameters for Standard Events

You can use the fbq('track') function to track the following standard events. Standard events also support parameter objects with specific object properties, which allow you to include detailed information about an event.

See list here: Standard Events and Object Parameters