I have enabled "Cache Mobile" option since my theme has additional mobile theme.
Is there a switch to get mobile view on dekstop?
In fact I need it to analyze mobile CSS with on-line tool.
Something like www.domain.com/?view=mobile
Don't know which plugin you talking about, but to simulate Mobile View on desktop open Chrome or Firefox and press Strg + Shift + M on your keyboard and you will see what you want to see, so there is no need for a online-tool.
There is no option or parameter in URL to display the mobile view on desktop. Which code (HTML, css,js,....) is used depends on User Agent, so you must request your page with a mobile device to get the code and the view for this device (User Agent).