If your game is a runner you can simply store the starting world location and subtract from the death world location, and then use the Vector Length node, which will return you a float value.
If its not linear, you will have to add in every tick the actual distance traveled in each frame. It will be something like:
Create a float TotalDistanceTraveled variable;
Event tick-> TotalDistanceTraveled += MovementComponent->Velocity->VectorLength * DeltaSeconds;