If the controller is turned to the “off” position and your sprinkler is still has one zone operating, it is likely a valve on the system has failed. You need to turn the water off to the system and contact the office for a service appointment. You can do this at the backflow device outside the house or at the sprinkler shut-off valve in your basement. 

HOWEVER, if this is the first time your sprinkler has run for the season it may just have debris in the valve. Often turning the water off then back on will flush the debris. Try that before you request service.

Alternately, if your controller is in the OFF position and it is still running as scheduled it may just be that the knob is not fully clicked into the OFF position. Wiggle the button or click away and back to see if that engages the off button.