First, if you completed the deferred successfully you can already check no or ignore the question have you ever been convicted because a deferred by its nature means you were not convicted. You could have been saying no the entire time.
What is on your record is an arrest. Again, I am working from the assumption you were put on deferred and successfully completed the terms and conditions and have been discharged without adjudication. I know that sounds like a mouth full and it is. I have had clients come see me for non-disclosure orders that did not understand that when they missed probation meetings, did not pay fines, or got into a minor scrape at some point they had violated the terms and conditions of deferred probation and had been adjudicated. It is unfair and in my opinion unethical, but probation officers will sometimes tell a probationer to "just sign here and you will stay on probation" without explaining to the defendant that he or she is judicially confessing to violating terms and asking the court to adjudicate and continue on probation - the paper in effect tells the Judge the signor did not complete deferred and ask the court to find them guilty and enter a conviction on the record in exchange for not going back to court - sometimes for something very minor.
Okay, now that we have that out of the way, you likely know if you are adjudicated or unadjudicated. If you are still unadjudicated and discharged at least 2 years ago, you can file a Motion for Non-Disclosure. This is manner you will prevent employers from even seeing you were arrested. It is similar to a juvenile record - it is there, but no one knows except the Court that did it and a few alphabet agencies you would rather avoid anyway. It can not be disclosed to anyone (the information is sealed and no one can use it).
You should hire a lawyer to help with the non-disclousre, there are many agencies that need to be properly notified, served, etc. Cost is variable by firm and jurisdiction, but plan on a filing fee of $300, process fees for cert mail to the list of agencies entitled to notice at $15 each (the court, the state police, the national criminal database, the local police, any arresting agency and any detention facility, the clerk of the court, the DA or County Attorney, the county sheriff where the crime occurred and if you were picked up by another agency on a warrant, that county's sheriff, and the police agency affecting the arrest). All told, it is generally between 10 and 14 service notifications bringing the court cost up to just shy of $500. Then the Attorney will have to be paid for his time and that also varies with the County/Jurisdiction based on the local prosecutor's policies and how difficult they make it.
I handle these types of matters in Collin County and would be happy to run the check for you and advise if you are eligible and if so, set you up with a consultation. Otherwise, I would recommend you find a local lawyer that knows the local system.
Answer Applies to: Texas
You can apply for an expunction.
Answer Applies to: Texas