can you be arrested for being hi but not having any drug stuff on you?

Yes, but with some explanations. 

1. A.R.S. § 13-3405 (A)(1) says that a person shall not knowingly possess or use marijuana. 
2. A.R.S. § 13-3406 (A)(1) says that a person shall not knowingly possess or use a prescription-only drug unless the person obtains the drug through a licensed prescriber. A person who violates this law is guilty of a class 1 misdemeanor. 
3. A.R.S. § 13-3407 says that a person shall not knowingly possess or use a dangerous drug, and a person who violates this law is guilty of a class 4 felony. 
4. Arizona DUI laws under A.R.S. § 28-1381(A)(1) says that it is illegal to operate a motor vehicle while a person is under the influence of any drug if the person is impaired to the slightest degree.