Hate to burst your bubble, but grabs physics degree.
The Voyager 1 probe is the slower of the two by a significant degree, however that is just a difference of about 2,000 miles per hour according to NASA. To do this calculation we need to convert to meters per second for the physics calculations. Voyager 1's speed then is 16999.49 meters per second.
Now, that's pretty fucking fast. Faster than an Earth sized planet's escape velocity so the only way for this to happen is for Voyager to have a direct encounter with the planet and that is not going to be pretty.
Since you said you wanted Voyager's message to be received by a civilization lacking advanced space travel, I'm going to assume you want to probe to hit the surface of the planet. However, with the speed it would be traveling at and its mass of 825.5 kilograms, it would impact with about 119,278,000,000 joules of Kinetic Energy. To put that in perspective, that's about the blast yield of a small nuclear weapon.
Unfortunately, this means that the probe and its message will most likely be vaporized on contact and cause severe damage to everything in about a 1 km radius of the impact zone.
That is then assuming that it doesn't explode in the atmosphere then the damage will be even more severe on the ground.