Yes, you have to claim all of your income on your tax return. Your former employer will issue a W-2 form for even one hour of wages and you are expected to report all of your income.
If you have moved since leaving that job, you should contact your former employer as soon as possible and give them your current address.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"