how to use capital letters in Post permalink

Using upper case may affected SEO:

URLs can be constructed using upper and lowercase or a mixture of both. Mixing the two or following standard grammar rules such as using a capital letter for a name can make your site structure unnecessarily complicated. You also run the risk of losing visitors who forget to use the required capital letter mid-way through the URL and then can’t access the page. The rule of thumb is stick to lowercase throughout. If you are redeveloping your URLs and come across pages using uppercase, create a permanent 301 redirect to a lowercase version to avoid confusion.