How to connect DRV-8835 to arduino
Try this code:

void setup() {
    pinMode(8, OUTPUT);//MODE
    pinMode(5, OUTPUT);//AENBL
    pinMode(7, OUTPUT);//APHASE
}

void loop() {
  pinMode(7, HIGH);//APHASE
  pinMode(8, HIGH);//MODE
  pinMode(5, HIGH);//AENBL
  delay(200);
  pinMode(5, LOW);//AENBL
}


Here is a description of the breakout board, this shows a requirement of PWM on AENBL for speed control. Try different  delays.