1. The smaller the black hole, the brighter and shorter lived it is. To get the black hole to live for any decent amount of time, it'd have to be travelling close to the speed of light for the effects of time dilation to extend it's life time from our perspective.
2. Detecting gravitational effects on a small scale is stupidly hard because of how weak gravity appears to be (compared to the other 3 forces: strong nuclear, weak nuclear, electromagnetic).
If you were to shine a laser and the tennis ball massed black hole travelled through the path of the laser, you wouldn't see any light missing because the wavelength of light would be larger than the black hole.
If you stopped the black hole (so it's not moving close to the speed of light), and tried to shine the laser at it for a greater effect: not only would you not see less light, you would actually see light shooting out of it so bright it'd be like putting your eye against many many atomic bombs because the Hawking Radiation would be so strong. (It'd also destroy itself in a blink of an eye)
You can increase the mass of the black hole to make it cooler and live longer. A 1,000 metric tonne black hole would live for around 46 seconds shedding radiation at an ever increasing amount before exploding into nothingness again. Assuming you could filter out the light coming from the black hole, you might see the phase of the laser light shift, but it'd all still end up at it's destination.
The greater problem would be trying to figure out how to shield the Earth from the amount of light shooting out of it.