Licensing is good way to enable your idea to be used, even if you yourself do not want to start a company with it.
Oxford Univerisity Innovation outline the use of licensing of University IP on their website with this great definition:
Licensing enables Oxford Univeristy Innovation to maintain ownership, and therefore control, of its IP whilst at the same time generating royalty income from the use of its IP by industry.
A license is an agreement involving the transfer of rights from one party (‘the licensor’) to the other (‘the licensee’). These rights commonly control the use (for copying, manufacture, sale etc.) of an IPR (a patent, copyright material, confidential know-how etc.).
Conversely, Oxford Univeristy Innovation have a list of IP which is available for licensing, so make sure you check that out if you're looking for a startup technology!