Spouses have an insurable interest in each other.
Insurable interest is required in order to buy life insurance on another person. Basically, it means you rely on the other person for financial support, or you stand to lose financially if that person were to die.
You can buy life insurance on your husband, but you may need his permission, signature on the application, and he may have to answer some health questions, or take a physical exam.
In addition, there are no exam life insurance plans you can apply for online and start the life insurance the same day, if you qualify for coverage. There's no exam, but there are some health questions.