Hi Pavan,
The best way to do that is probably to use a custom marker template to display the text value. You can do that as below:

$("#container").igDataChart({
                width: "500px",
                height: "500px",
                dataSource: currData,
				crosshairVisibility: "visible",
                axes: [{
                    name: "xAxis",
                    type: "categoryX",
                    label: "Label",
					interval: 1
                },
                {
                    name: "yAxis",
                    type: "numericY",
					labelTextColor: "blue",
                }],
                series: [{
                    name: "series1",
                    title: "Test Series",
                    type: "column",
                    xAxis: "xAxis",
                    yAxis: "yAxis",
                    valueMemberPath: "Value",
					markerTemplate: {
                        measure: function (measureInfo) {
                            var cont = measureInfo.context;
                            var data = measureInfo.data;
                            var name = "null";
                            if (data.item() != null) {
                                name = data.item().Value.toString();
                            }
                            var height = cont.measureText("M").width;
                            var width = cont.measureText(name).width;
                            measureInfo.width = width;
                            measureInfo.height = height;
                        },
                        render: function (renderInfo) {
                            var ctx = renderInfo.context, radius;
                            if (renderInfo.isHitTestRender) {
                                ctx.fillStyle = renderInfo.data.actualItemBrush().fill();
                            } else {
                                ctx.fillStyle = "black";
                            }

                            var data = renderInfo.data;
                            var name = data.item().Value.toString();
                            var halfWidth = renderInfo.availableWidth / 2.0;
                            var halfHeight = renderInfo.availableHeight / 2.0;
                            var x = renderInfo.xPosition - halfWidth;
							
                            var y = renderInfo.yPosition - ((halfHeight * 2.0) + 5.0);
							if (y < 0) {
								y += (halfHeight * 4.0);
							}

                            if (renderInfo.isHitTestRender) {
                                ctx.fillRect(x, y, renderInfo.availableWidth, renderInfo.availableHeight);
                            } else {
                                ctx.textBaseline = "top";
                                ctx.fillText(name, x, y);
                            }
                        }
                    }
                }],
                horizontalZoomable: true,
                verticalZoomable: true,
                windowResponse: "immediate"
            });

We are providing a simplified way of providing text markers in 12.2 that would reduce the amount of code required here.
Hope this helps!

-Graham