There’s no way that you’d be able to kiss your teacher’s navel without her knowing – not that you should even be trying – and she probably wouldn’t react very well if you attempted it.
In most places, it’s illegal for you to have that kind of a relationship with your teacher anyway (well, if you’re underage) and your teacher would probably lose her job if she let you kiss her – even if it was on the navel.
You should probably just keep these urges to yourself – by all means, fantasize about kissing her navel, but don’t actually do it!