What you are referring to is called the Google Snippet and is also called the Meta Description Tag. For a short video explaining how Google selects the wording for the snippet, see: http://www.seroundtable.com/archives/015452.html
For individual Hubs and for your profile page, Hub pages does not provide a means for you to enter the Meta Description Tag and, you are right, the 'Summary' feature will not be picked up by search engines.
But you can create your own Meta Description Tag by manipulating the text in the first few sentences of you profile and/or your Hub. Write these sentences exactly as you would write the Summary on a Hub. Limit the text to 157 characters.
If you search on Google for "Writer Fox", my Hubpages profile should be the first listing on the SERP and you will see that the Google Snippet is exactly what I wrote as the introduction to my profile.
There are times when Google will not use your selected text for the Google Snippet. This occurs when Google finds other text on your webpage that more specifically answers the search query, and you cannot control this.
For more information on writing an effective Meta Description Tag/ Google Snippet, see my Hub "What is SEO?" and select IV – 3 (SEO Meta Tags) from the Table of Contents.