If the parent who is not working is receiving unemployment 

benefits:

Attach Unemployment Compensation

Unemployment Compensation benefits are attachable for child support. Only the government child support agencies can attach unemployment compensation file an application for this service. You will most likely only receive a portion of the support due because unemployment benefits are usually not a large amount of money.
You need to know the nonpaying parent’s full name, correct address and social security number.

Obtain Seek Work Order

If the nonpaying parent is not collecting unemployment, request court action to issue a “seek work” order that requires the nonpaying parent to provide proof that they are looking for work.  Request the court order the unemployed parent o report in every two weeks to the government child support agency to show proof they are seeking employment. Often if they are really working or working under-the-table it is easier copay than report in.  Also they fail to report in they can be brought up on Contempt of Court Charges.
You can also place liens on property to secure arrearage if the parent is unemployed and if they sell the property you might be entitled to receive some back support due out of the proceeds from the property sale.