To release a song containing a sample you must be granted permission from the rights holders that own the music composition as well as the rights holders that own the sound recording.
For example, to sample a lyric or piece of instrumentation, you would need permission from both the owners of the lyrics and the underlying composition (usually the music publishers) and the owners of the recording (usually the record label). This permission is normally in the form of a sample clearance.
If you use a piece of someone else's composition (e.g. a lyric, chord, guitar riff etc.) to include in your song, but rather than using that piece of the original recording you re-record the lyric or chord, guitar riff etc, then you have used an interpolation rather than a sample. While you would not need the permission of the owner of the original sound recording (because you didn't use the recording), you would still need the permission from the owner of the original composition. A mechanical license will not cover this use, instead you will need to negotiate directly with the owners/rights holders.
If you create a release including samples, please select this option when creating your release. You will need to fill out this form with your details and send through the correct documentation. After you have provided this and it has been approved, only then will your release be reviewed and sent to stores.