Thank you for your interest in Aspose products.
I am afraid, with current implementation of Aspose.BarCode for .NET, you cannot set a caption for right and left sides of the barcode symbol. BarCodeBuilder class has two properties, CaptionAbove and CaptionBelow that take an instance of Caption class. So, it is possible to customize the text, alignment, font, color and space of the caption if it is above or below the barcode symbol. Moreover, you can also influence the caption text alignment by setting the TextAlign property exposed by the Caption class.
Please check below linked technical articles for your reference,
Feel free to write back in case you have further inquiries or comments.