Is there a drag and drop software to create apps for cell phones and computers?

It’s based on a question that I asked about basic programming. I got a real cool app in mind but have absolutely no idea how to write it or where to begin. I am too scared to tell anybody about my app that I have in mind because I know someone will steal my idea. It happened to me before and the a-hole made a fortune from my idea. Please keep in mind I don’t know anything about programming or writing programs or apps. The closest I got to programming was writing twinkle little star in DOS back in the 90’s with help from a book.