Servo PWM probe for Arduino. Assuming up edge of evey port is aligned.

pwm_reader.ino

const int NPIN = 2; // pin count
const int PINS[NPIN] = {2, 3}; // input pins

volatile long long t0 = 0, t[2] = {0};

void edge_function(int pin) {
  byte level = digitalRead(PINS[pin]);
  if(level && pin == 0) { // react to up edge of only pin 0.
    t0 = micros();
    Serial.print((int)t[0]);
    Serial.print("\t");
    Serial.print((int)t[1]);
    Serial.println();
  }
  if (!level) {
    t[pin] = micros() - t0;
  }
}

void edge0() {
  edge_function(0);
}

void edge1() {
  edge_function(1);
}

void setup() {
  Serial.begin(115200);
  pinMode(PINS[0], INPUT_PULLUP);
  pinMode(PINS[1], INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(PINS[0]), edge0, CHANGE); // only pin 0 need up edge detect.
  attachInterrupt(digitalPinToInterrupt(PINS[1]), edge1, FALLING); // otherwise just falling edge is needed.
}

void loop() {
  // put your main code here, to run repeatedly:

}