Do you earn any income from investments or hobbies?

"Do you earn any income from investments or hobbies?"

If you are active in the stock market, then you can mention something like that. Another income from investment is from your savings account or mutual funds. Whatever it is, simply tell them what it is.

"I have a savings account that I earn a little extra income from."
"I have some mutual funds that perform about 8% a year."
"I have some investments in the stock market."