At Compose (YC, S11) we had a two part hiring method. The first was a blind work-sample. You had unlimited time to complete it. Identifying information was obfuscated and graders would yes/no objective criteria. The best samples proceeded to the "work day".

During the work day, you'd join is in Slack for 8 hours. You'd need to ask probing questions to mock-up our infrastructure and pitch a feature based on "how we work".

One could try to cheat on the first part, but there is no chance one could have bamboozled us during the work day.

For our technical writing positions we had some instances of outright plagiarism, but no instances of anyone trying to cheat the coding sample.